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A new approach to the suppression of molecular ions in secondary ion mass spectra of insulating specimens is reported. Using a Cameca IMS 3f instrument, with unconventional primary beam conditions and uncoated samples, it has been possible to almost eliminate the contribution of molecular ions to the mass spectrum. This has resulted in excellent discrimination for major and trace element detection in these materials, including complete resolution of the rare earth elements in a number of minerals.

Emploi de la spectrometrie SIMS et XPS et de l'oxydation a 18 O 2 pour etudier la distribution de l'oxygene a la surface du charbon en relation avec d'autres elements specifiques. Plusieurs derivatisations chimiques ont ete observees a la surface d'un charbon oxyde

Nickel‐18% chromium binary alloy and alloy 600 (77% Ni, 16% Cr, 8% Fe) have been oxidized at 600 °C for periods of several minutes under O2 pressures of

The free radicals •Mn(CO)5 and •Co(CO)4 have been produced by the pyrolysis of Mn2(CO)10 and Co2(CO)8 in graphite flow reactors. The effusing molecular beams from these reactors were analyzed mass spectrometrically. Evidence is presented for the following equilibria[Formula: see text]From the temperature dependence of the equilibrium constants, enthalpy changes of 24.9 ± 2 and 14.5 ± 2 kcal/mole, respectively, have been obtained. These enthalpy changes give D(Mn—Mn) = 21 ± 3 kcal/mole and D(Co—Co) = 13 ± 3 kcal/mole, which substantiate the earlier literature values based on electron impact measurements.

The mass spectra and appearance potentials for the major ions from Ni(CO)4, Fe(CO)5, Cr(CO)6, Mo(CO)6, W(CO)6, and V(CO)6 have been measured. Heats of formation have been calculated for 39 ions of the type M(CO)n+, where M = Ni, Fe, Cr, Mo, W, and V. The mean metal–carbon bond dissociation energies have been calculated for both the neutral molecules and the parent ions. From a comparison with the available thermochemical data for the neutral molecules it is concluded that the mean vanadium–carbon bond dissociation energy is 28 kcal/mole and the heat of formation of V(CO)6 vapor is − 204 kcal/mole.

ESR spectra of the ScS and YS molecules in their ground 2Σ+ states were measured while trapped in solid argon or neon matrices at 4°K. g tensors and hyperfine structure constants for interaction with the metal nuclei were accurately derived, within the ambiguity of multiple matrix sites. Earlier ESR data on ScO were also more accurately analyzed, and a comparison is given of the magnetic parameters for the diatomic oxide and sulfide molecules of Sc, Y, and La. The ir spectra of ScS and YS in argon matrices yielded bands at 554 and 483 cm−1, respectively, and the A 2Π← X 2Σ transition of YS was observed at 7300 A.

The application of secondary ion mass spectrometry (SIMS) to the study of organic polymeric surfaces has increased rapidly in recent years and has been extended to the organic constituents of coals. The detection of inorganic constituents in such organic matrices using SIMS is limited by the strong background contribution from molecular ions. A method for the suppression of molecular ions in SIMS spectra, known as specimen isolation (SI) has been introduced. The application of the SI-SIMS technique has now been extended to the analysis of some highly insulating organic polymer and coal surfaces. Examples of the results obtained are given.

Accurate characterization of reacted catalyst surfaces usually requires that specimen contact with air or moisture be avoided between rection and analysis. X-ray photoelectron spectroscopy (XPS) is now a routine technique for determining the composition and chemistry of catalyst surfaces. In the past few years a number of specialized catalyst reaction cells have been designed to be attached more or less direction to the analytical chamber of the spectrometer. However, most of these cells are intended to evaluate individual properties of a catalyst formulation, rather than for use in a full reaction sequence. The authors developed an on-line reactor for the study of supported Co-Mo catalysts within which reduction, sulphidation and thiophene reaction stages can be carried out at temperatures up to 500{sup 0}C and pressures to 10 atmospheres. It is described in this paper.

Supported cobalt-molybdenum catalyst surfaces have been prepared in thin film form for use in the study of hydrodesulphurization (HDS) mechanisms. The films consist of overlayed layers of cobalt and molybdenum (∼5 nm thick) on an alumina substrate which are calcined, reduced and sulphided before being reacted at 230–350°C with a circulating thiophene hydrogen gas mixture in a reactor directly attached to an X-ray Photoelectron Spectrometer (XPS). The sulphided surfaces of certain of the thin film compositions were found to exhibit detectable HDS activity even though their surface areas were very low. Increased pressure of the C 4 H 4 S/H 2 gas resulted in increased activity. High resolution XPS studies revealed the presence of at least two other molybdenumsulphur species in addition to MoS 2 . These are ascribed to cationic and anionic sites on the Co-Mo-S surface phase presumed to have formed. HDS activity is found to correlate well with the measured concentration of these sites. Increased pressure results in an increase in these sites, as well as an increase in the sulphidation of the alumina support.

Aqueous oxidation of the nickel‐based alloy Inconel‐600 has been studied using x‐ray photoelectron spectroscopy as the primary means of determining the elemental composition and chemistry of the surface films produced. Composition profiles of the entire film thickness back to the metal‐oxide interface were determined using ion bombardment for controlled removal of successive surface layers. Samples of the alloy were exposed to aqueous attack in static and continuous autoclaves at 285°C for periods of 1–168 hr. The pH range 7–14 was studied and the dissolved oxygen concentration was varied from using hydrogen, argon, and oxygen overpressures. In hydrogen‐saturated water of pH 10, a thin (

The surface of Monel-400 alloy was exposed to high pH, aqueous corrosion at 285~ under both oxidizing and reducing conditions. After exposures lasting from 0.3 to 335 hr the surfaces were examined by x-ray photoelectron spectroscopy, scanning electron microscopy, and other techniques. Under reducing conditions, no corrosion film forms on the metal surface, but under oxidizing conditions, the first corrosion layer which forms at the solution interface is entirely Ni(OH)2. This hydroxide, which persists for long times at pH ,.~ 10 but which rapidly converts to NiO at pH ,., 14, is shown to result from a Precipitation process. The composition of the corrosion film is determined by the relative solubilities of nickel and copper at the interface. A composition profile of the corrosion layer beneath the outermost film shows :a gradual increase in cuprous ion concentration with increasing depth, probably due to solid-state migration. This suggests that the aqueous corrosion of Monel-4O0 involves both solid-state oxide growth and an ionic dissolution and precipitation mechanism.

Exposing polypropylene (PP) to ozone in the presence of UV light is a simple and effective way of modifying its surface to improve its wettability and adhesion. Atomic force microscopy (AFM) showed a dramatic change in the morphology and a clear increase in the adhesion force resulting from the modification of a PP film by UV/ozone exposure. A relationship has been demonstrated between a change in surface energy (measured by wetting contact angle) and the adhesion force (measured by AFM).